msg.h

, msg

Synopsis

Description

The <sys/msg.h> header defines the following data types through typedef:

msgqnum_t

used for the number of messages in the message queue

msglen_t

used for the number of bytes allowed in the message queue

These types are unsigned integer types that are able to store values
at least as large as a type unsigned short.

The <sys/msg.h> header defines the following constant as a message operation flag:

MSG_NOERROR

no error if big message

The msqid_ds structure contains the following members:

struct ipc_perm msg_perm Operation permission structure.
msgqnum_t msg_qnum Number of messages currently on
queue.
msglen_t msg_qbytes Maximum number of bytes allowed
on queue.
pid_t msg_lspid Process ID of last msgsnd(2).
pid_t msg_lrpid Process ID of last msgrcv(2).
time_t msg_stime Time of last msgsnd().
time_t msg_rtime Time of last msgrcv().
time_t msg_ctime Time of last change.

The pid_t, time_t, key_t, size_t, and ssize_t types are defined as described
in <sys/types.h>. See types(3HEAD).